The present invention relates to electric switches of the type used to energize or de-energize an electric appliance, and in particular to an electric switch having incorporated therein a circuit breaker for de-energizing the appliance in the event of an overload.
An electric appliance such as a vacuum cleaner or the like powered by conventional AC current is energized or de-energized by actuating a thumb-operated switched. The circuit for an appliance includes an electric motor which may become impaired by an object that obstructs the rotation of the motor. In such an event, the motor will draw an excess of current which if allowed to continue will cause damage to the circuitry of the motor or other components of the appliance. To prevent such an overload, it is desirable that the appliance include a circuit breaker which can be easily reset by the operator.
A switch incorporating a built-in circuit breaker is disclosed by Jang, U.S. Pat. No. 5,541,569. The circuit breaker of Jang includes a pivotable switch member for opening and closing the contacts of the switch, and a circuit of the switch includes a bimetal actuator. In normal operation, a contact on the bimetal actuator extends through a hole in a generally planar indicator member that is urged by a spring to an extended position. The indicator member is retained in the retracted position by the contact on the bimetal actuator that extends through the hole and abuts a second contact on the opposite side of the indicator member. In the event of an overload, the bimetal actuator causes the contact attached thereto to be retracted through the hole, thereby allowing the insulated indicator to move to the extended position. A portion of the insulated indicator then becomes wedged between the contact on the bimetal actuator and the second contact on the opposite side of the actuator thereby retaining the circuit open until the bimetal actuator is manually depressed by the operator.
An appliance such as a vacuum cleaner must be manufactured to operate on a daily basis for a number of years. During the course of the normal life of the appliance, a circuit breaker incorporated into the switch may be called into operation several hundred times. The repeated movement of the actuator erodes away the portion of the insulating material wedged between the two contacts. After a given number of uses the portion of an insulating member that has been repeatedly wedged between spring loaded contacts may become so worn away that the circuit breaker will fail to operate when called upon. It would be desirable, therefore, to provide an improved switch with an incorporated circuit breaker that does not rely upon interposing an insulating member between spring loaded contacts.
Briefly, the present invention is embodied in an electric switch for completing a circuit having a circuit breaker therein where the switch includes a manually operated actuator, a first contact, a second contact, the first contact moveable between a first position and a second position in response to an excessive current, and the second contact moveable between a first orientation and a second orientation in response to movement of the actuator. The switch includes a bimetal member and means for joining the first contact to the bimetal member wherein the first contact is moved from the first position to the second position in response to an electric current above a given threshold.
The second contact is moveable between the first orientation and the second orientation in response to movement of the actuator. In normal operation, the first contact is in an abutting relationship with the second contact when the second contact is in the first orientation and the first contact is in the first position and the contacts are spaced from one another when the first contact is in the second position, and are also spaced from one another when the second contact is in the second orientation.
The switch further includes an indicator that is moveable between an extended position indicative of a broken circuit and a retracted position indicative of a closed circuit, and means, such as a spring, for urging the indicator towards the extended position. A catch releasably retains the indicator in the retracted position. A means for releasing the catch is responsive to the movement of the first contact to the second position. The indicator also has means thereon for retaining the second contact in its second position while the indicator is in the extended position.
An operator will manually operate the actuator to turn the appliance on, thereby moving the second contact from its second orientation to its first orientation where it will abut the first contact and close the circuit. In the event of an overload in which the current exceeds the threshold as determined by the bimetal member, the bimetal member will cause movement of the first contact from its first position to its second position where it is spaced from the second contact thereby breaking the circuit. The same movement that breaks the circuit releases the spring loaded overload indicator, allowing it to be moved by the spring to the extended position. The movement of the indicator to the extended position will also lock the first contact in the second position thereby preventing the closing of the circuit after the bimetal member cools.
After an operator has checked the device and remedied the cause of the overload, the indicator can be manually depressed, returning it to the retracted position where it can again be engaged by the means for retaining. Once the indicator has been reset, the bimetal member can move the first contact back to its first position, thereby resetting the circuit breaker.
The invention further includes a first connector electrically connected to the first contact and a second contact electrically connected to the second contact. A third connector connects to a circuit for operating a lamp in the actuator, the lamp being illuminated when the actuator is in the on orientation and not illuminated when the actuator is in the off orientation. The lamp circuit includes the second connector, the third connector, and a switch operated by the actuator that is closed when the second contact is in the first orientation and opened when the second contact is in the second orientation.